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Proceedings Paper

3D characterization of the forces in optical traps based on counter-propagating beams shaped by a spatial light modulator
Author(s): Martin V. Kristensen; Thue B. Lindballe; Anton P. Kylling; Darwin Z. Palima; Jesper Glückstad; Soren R. Keiding; Henrik Stapelfeldt
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Paper Abstract

An experimental characterization of the 3D forces, acting on a trapped polystyrene bead in a counter-propagating beam geometry, is reported. Using a single optical trap with a large working distance (in the BioPhotonics Workstation), we simultaneously measure the transverse and longitudinal trapping force constants. Two different methods were used: The Drag force method and the Equipartition method. We show that the counterpropagating beams traps are simple harmonic for small displacements. The force constants reveal a transverse asymmetry as κ- = 9.7 pN/μm and κ+ = 11.3 pN/μm (at a total laser power of 2x35 mW) for displacements in opposite directions. The Equipartition method is limited by mechanical noise and is shown to be applicable only when the total laser power in a single 10 μm counter-propagating trap is below 2x20 mW.

Paper Details

Date Published: 28 August 2010
PDF: 12 pages
Proc. SPIE 7762, Optical Trapping and Optical Micromanipulation VII, 77623E (28 August 2010); doi: 10.1117/12.866479
Show Author Affiliations
Martin V. Kristensen, Aarhus Univ. (Denmark)
Thue B. Lindballe, Aarhus Univ. (Denmark)
Anton P. Kylling, Aarhus Univ. (Denmark)
Darwin Z. Palima, Technical Univ. of Denmark (Denmark)
Jesper Glückstad, Technical Univ. of Denmark (Denmark)
Soren R. Keiding, Aarhus Univ. (Denmark)
Henrik Stapelfeldt, Aarhus Univ. (Denmark)


Published in SPIE Proceedings Vol. 7762:
Optical Trapping and Optical Micromanipulation VII
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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